15 minute timer latching

Thread Starter

Planetping

Joined Feb 1, 2016
3
Hi!

I need to build a timer circuit that allows a powered microphone to go live for 15 minutes when a momentary switch is pushed. An led indicator is also required to light for the 15 minute duration.

I am thinking a 555 monostable design connnected to the positive side of the mic/led power. Tried a few configurations but could do with a working prototype ASAP!!

Thanks in advance

PP
 

ronv

Joined Nov 12, 2008
3,770
Hi!

I need to build a timer circuit that allows a powered microphone to go live for 15 minutes when a momentary switch is pushed. An led indicator is also required to light for the 15 minute duration.

I am thinking a 555 monostable design connnected to the positive side of the mic/led power. Tried a few configurations but could do with a working prototype ASAP!!

Thanks in advance

PP
What voltage goes to the microphone?
 

AnalogKid

Joined Aug 1, 2013
8,540
Lotsa timer modules on ebay, some with digital setpoints and a display. What is the microphone current draw at 12 V? Also, do you really need to switch power to the mic, or just enable/disable its output?

ak
 

Thread Starter

Planetping

Joined Feb 1, 2016
3
switching the output is and option as long as an indicator led can also be switched. Looking like I may need 100's of these so the easier to make the better!
 

Dodgydave

Joined Jun 22, 2012
9,318
Switching the output is easy, mosfet or relay, you haven't said which timer you're using, if its for mass production then a pic or other tiny microcontroller is best, forget the 555 timer its useless.
 

AnalogKid

Joined Aug 1, 2013
8,540
IF the OP has a PIC programmer
AND IF he is fluent in PIC assembler OR PIC Basic OR C++
THEN the cost of clean regulated power for the PIC still has to be figured into the budget.

While this application might be beyond the reach of a 555, there are other timer solutions. I think a dedicated 4060 + 4093 design could compete even without the PIC's programming overhead.

Here is the original form:

I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail.
- Abraham Maslow, The Psychology of Science: A Reconnaissance (1966), Ch. 2, p. 15.

ak
 
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